In the book "How to Attain Knowledge of the Higher Worlds?" the path to higher knowledge is presented up to the encounter with the two "guardians of the threshold." In this writing, the relationships that the soul finds with the various worlds as it progresses through the successive stages of knowledge will also be presented. As a result, we have what we can call "Gnostic teaching of occult science," that is, the science that remains hidden in the usual way of knowing. Instead of "occult science," we could say "esoteric science," because the results of this science are not kept hidden but are printed in books accessible to everyone.